DC-magnetisation studies in the La1-xSrxCoO3 (x <= 0.4) system

The magnetic field and temperature dependence of DC-magnetisation in polycr ystalline samples of La1-xSrxCoO3 (x less than or equal to0.4) (LSCO) perov skite system is being, studied using a SQUID magnetometer. We find that for Sr-concentration, x greater than or equal to0.2, a sharp increase in magne tisation is observed in the temperature regime of 200-230 K. Strong thermom agnetic irreversibility (i.e. M-ZFC not equal M-FC) in the entire investiga ted composition regime is found in this system. Furthermore, we observed a mild hysteresis and small coercivity in the. M-H scans performed at various temperatures in samples with x greater than or equal to0.2. Them observed magnetic behaviour in these samples clearly indicates that for x greater th an or equal to0.2, LSCO is a soft ferromagnet. We interpret that the observ ed thermomagnetic irreversibility arises from large magnetocrystalline anis otropy, which at low external applied magnetic fields effectively pins the ferromagnetic (FM) domains. (C) 2001 Elsevier Science BY. All rights reserv ed.